The present invention relates to metal clays with refractory stains.
Upon sintering, jewelry-metal clays form pure or almost pure jewelry-metal objects that retain the basic shape of the jewelry-metal clay. The clays contain a jewelry-metal powder and a binder; the binder is mostly removed during the sintering process. Jewelry-metal clays are described in U.S. Pat. Nos. 5,376,328 and 5,328,775. Jewelry-metal clay is referred to in the trade as precious metal clay, or PMC, and is available from RIO GRANDE, 7500 Bluewater Road N.W., Albuquerque, N.Mex., 87121, among others.
The ability to color jewelry-metal objects is limited. Jewelry-metal gold is an excellent example. Although white, rose, green, and varying shades of yellow gold are known, each is made by alloying pure gold with a second metal. The achievable color variation in any jewelry-metal, whether 24 karat gold, 18 karat gold, 14 karat gold, 10 karat gold, Nu-gold (88% wt. Cu 12% wt. Zn), fine silver, sterling silver (92.5% wt. Ag/7.5% wt. Cu), nickel silver (65% wt. Cu/18% wt. Ni/17% wt. Zn), platinum, palladium, ruthenium, rhodium, aluminum, brass, lead, nickel, iridium, indium, copper, zinc, or combinations thereof, is typically limited to the alloys these metals form. Accordingly, there is a need to expand the varieties of colors of jewelry-metal articles.
Refractory stains have many uses and are widely used to color ceramics. Prior to firing, the stain is incorporated into the slip and/or applied as a glaze. The stains are prepared by mixing together metal oxides and various inorganic and metal binders, which are fired for color stability, and then ground.
In a first aspect, the present invention includes a composition for forming metal objects, including first particles containing a jewelry-metal, and second particles including a refractory metal oxide; The composition may be made by mixing these ingredients together.
In a second aspect, the present invention includes a metal object, containing a jewelry-metal; and second particles containing a refractory metal oxide, in the jewelry-metal.